Saw this in another thread — it’s possible to stop individual programs from ever showing up in Up Next. This is in Shows > [show] > [More, if you’re looking at an individual episodes] > gear button > Show Settings > Include in Up Next.

I wish I had known about this option months ago — it solves a lot of my issues with Up Next as I can leave it for those programs (e.g. news programs) where it makes sense.